1. Field of the Invention
This invention relates to cleaning apparatus for electrophotographic copier/duplicators, and more particularly to a mechanism for sensing an overload to the cleaning apparatus and accordingly shutting down the copier/duplicator.
2. Description of the Prior Art
Modern high speed electrophotographic copier/duplicators make document reproductions by exposing an electrically charged photoconductive member to a light image of the document to be copied. The light image selectively discharges the photoconductive member to form a latent image charge pattern on the member corresponding to the document. An oppositely charged developer material is brought into contact with the latent image to develop the image. Subsequently the developed image is transferred to a receiver sheet and fixed to the sheet by heat and/or pressure to yield the desired reproduction.
The developer material is generally a resinous powder referred to as toner. In transferring the toner to the receiver sheet, because of the nature of the material, it is virtually impossible to make a complete transfer. If the residual toner material is not removed from the photoconductive member prior to reusing the member, subsequent images formed on the member will be degraded; moreover, the toner material may scatter throughout the copier/duplicator to contaminate the internal structure of the copier apparatus to adversely effect its overall operation. Therefore, it is desireable to include apparatus for cleaning the photoconductive member immediately after transfer of the image from the photoconductive member to the receiver sheet.
Typical apparatus for cleaning the photoconductive member of an electrophotographic copier/duplicator are shown and described in U.S. Pat. Nos. 3,615,813 and 3,838,922 and Research Disclosure Bulletin, Vol. No. 143 at Page 20, (published by Industrial Opportunities, Ltd., Homewell, Havant, Hampshire, P09 1EF, U.K.), the publication entitled "Electrophotographic Copier Erase and Cleaning Apparatus". Briefly, the cleaning apparatus include a rotating brush contacting the photoconductive surface. A vacuum atmosphere surrounds the brush and draws toner material swept up by the brush through a filter arrangement. Under adverse circumstances, it is possible for the filter to become overloaded with toner material. When this occurs the material may be blown out into the copier/duplicator or its surrounding work space creating a hazardous condition for the machine, its operator, and the surrounding environment.